System And Method For Cooling A Device Subjected To Heat In A Vehicle, Particularly An Aircraft

ABSTRACT

A cooling system ( 10 ) for cooling a heat-loaded device ( 14 ) in a vehicle, particularly an aircraft, comprises a cooling circuit ( 12 ), through which flows a heat transfer fluid and which is thermally coupled to the heat-loaded device ( 14 ) in order to remove heat from the heat-loaded device ( 14 ). A heat exchanger ( 18 ) of the cooling system ( 10 ) comprises a section ( 20 ) which is thermally coupled to the outside environment via an outer skin ( 22 ) of the vehicle.

The present invention relates to a system and a method for cooling a heat-loaded device in a vehicle, particularly an aircraft.

On board an aircraft there are provided a large number of different technical devices which produce heat and have to be cooled to ensure reliable operation. These technical devices include, for example, the electronic control components of the aircraft. Furthermore, it is frequently necessary for goods transported on board an aircraft or food required for the passengers and crew to be kept cool. Finally, it may be desirable to support the air conditioning system of the aircraft. Various aircraft cooling systems which utilise ambient air for cooling heat-loaded devices on board the aircraft are known from the prior art.

From DE 38 12 739 C1, for example, it is known to arrange a cooling chamber inside a galley of an aircraft close to the outer skin of the aircraft and to provide a cold air chamber between the cooling chamber and the outer skin of the aircraft. In the cold air chamber, air as the cold transfer medium is cooled by heat exchange with the aircraft outer skin designed without a heat insulating layer and is subsequently supplied to the cooling chamber for cooling a service trolley filled, for example, with drinks and food to be cooled. The cooling system known from DE 38 12 739 C1 has the disadvantage that, owing to the use of air as the cold transfer medium, large air volume flows are required in order to carry off large quantities of heat. The cold air chamber therefore takes up a comparatively large amount of installation space. Moreover, a heat-loaded device cooled by means of the cooling system described in DE 38 12 739 C1 has to be arranged in spatial proximity to the aircraft outer skin, in order to avoid pressure losses and consequently impairment of the heat removal from the heat-loaded device.

DE 42 27 965 A1 describes a cooling system for cooling food stored on board an aircraft which comprises a surface heat exchanger, through which flows a heat transfer fluid to be cooled. The surface heat exchanger is mounted on an outer surface of an aircraft outer skin, so that the heat transfer fluid flowing through the surface heat exchanger is cooled by heat exchange with the ambient air. However, the surface heat exchanger mounted on the outer surface of the aircraft outer skin increases, disadvantageously, the aerodynamic drag and consequently the fuel consumption of the aircraft. Moreover, conduits for the heat transfer fluid flowing through the surface heat exchanger have to be led through the aircraft outer skin, resulting in increased mounting complexity and risk of leakage.

Finally, DE 103 61 645 A1 discloses a cooling system for cooling heat-producing devices on board an aircraft, in which a refrigerating machine utilises ambient air from outside the aircraft pressurised fuselage as a heat sink for heat release and releases hot exhaust air to the environment outside the aircraft pressurised fuselage. In order to ensure proper ambient air supply to the refrigerating machine and proper exhaust air removal from the refrigerating machine, corresponding air inlet and air outlet openings have to be provided in the aircraft outer skin. However, this again disadvantageously increases the aerodynamic drag and consequently the fuel consumption of the aircraft.

The object of the present invention is to provide a flexibly usable, installation space-saving cooling system for cooling a heat-loaded device in a vehicle, particularly an aircraft, which utilises ambient air for cooling the heat-loaded device.

To achieve this object, a cooling system according to the invention for cooling a heat-loaded device in a vehicle, particularly an aircraft, comprises a cooling circuit, through which flows a heat transfer fluid and which is thermally coupled to the heat-loaded device in order to remove heat from the heat-loaded device. Furthermore, the cooling system according to the invention comprises a heat exchanger comprising a section which is thermally coupled to the outside environment. “Outside environment” is understood here to mean the outside atmosphere. The heat exchanger of the cooling system according to the invention consequently utilises the cooling energy contained in the ambient or outside air to cool the heat transfer fluid flowing through the cooling circuit to a desired low temperature. The section of the heat exchanger is thermally coupled to the outside environment via the outer skin of the vehicle. In other words, the thermal coupling between the section of the heat exchanger and the outside environment is realised by a thermal coupling of the heat exchanger section to the vehicle outer skin. The heat exchanger itself is, however, arranged inside the vehicle.

By utilising the vehicle outer skin for the thermal coupling of the heat exchanger section to the outside environment, the heat exchanger can be constructed in a particularly installation space-saving manner. Moreover, the direct coupling of the heat exchanger to the outside environment makes it possible to carry off even large quantities of heat particularly effectively. With the aid of the cooling circuit, a heat-loaded device which is not arranged in the immediate vicinity of the aircraft outer skin can also be supplied with cooling energy by the cooling system according to the invention. As a result, the installation site of this heat-loaded device can be flexibly chosen. A further advantage of this cooling system according to the invention is that it enables the utilisation of the cooling energy containing ambient or outside air without it being necessary, for this purpose, to mount a heat exchanger on an outer surface of the vehicle outer skin or form air inlet and air outlet openings or leadthroughs for conduits in the vehicle outer skin. Consequently, the aerodynamic drag of the vehicle is not increased by the heat exchanger of the cooling system according to the invention, so that an increase of the fuel consumption of the vehicle can be effectively avoided. Finally, in the case of the cooling system according to the invention, by utilisation of the cooling energy contained in the ambient or outside air, the use of an additional refrigerating machine for cooling the heat transfer fluid flowing through the cooling circuit can, where appropriate, be dispensed with, depending on the particular application or the system architecture.

Preferably, the cooling system according to the invention is provided for cooling a heat-loaded device for use on board an aircraft. The section of the heat exchanger thermally coupled to the outside environment is then thermally coupled to the out-side environment via an aircraft outer skin. Preferably, the aircraft outer skin is not provided with an inner insulation, in a region in which it is thermally coupled to the heat exchanger section to produce a thermal coupling of the heat exchanger section to the outside environment, in order to enable optimal heat removal to the ambient or outside air. It is, however, possible to provide a surface of the heat exchanger facing away from the outside environment with an insulation.

The section of the heat exchanger thermally coupled to the outside environment is thermally coupled to the outside environment preferably via a section of the aircraft outer skin arranged in the region of an aircraft fuselage lower shell. Such a configuration is expedient particularly when the aircraft outer skin is provided continuously with an inner insulation in the region of an aircraft fuselage upper shell, while an inner insulation of the aircraft outer skin can be dispensed with at least in sections in the region of the aircraft fuselage lower shell.

In principle, for proper functioning of the cooling system according to the invention, it is merely necessary for a section of the heat exchanger to be thermally coupled to the vehicle outer skin in order to produce a thermal coupling of the heat exchanger section to the outside environment. For this purpose, the heat exchanger can be connected, for example, to an inner surface of the vehicle outer skin in order to enable a large-area heat transfer. Alternatively to this, however, it is also conceivable to integrate the heat exchanger in the vehicle outer skin in such a way that the section of the heat exchanger thermally coupled to the outside environment is formed by a section of the vehicle outer skin itself.

Preferably, the heat exchanger comprises a conduit which is thermally coupled to the cooling circuit. The conduit of the heat exchanger can be directly integrated in the cooling circuit and the heat transfer fluid circulating in the cooling circuit can flow through the conduit. Alternatively to this, however, a merely thermal coupling of the conduit of the heat exchanger to the cooling circuit through which flows heat transfer fluid is also conceivable. The conduit of the heat exchanger is preferably formed such that it occupies a large part of the area of the heat exchanger in order to enable optimal heat transfer to the ambient or outside air. For example, the conduit can extend with a plurality of turns through the heat exchanger.

The conduit of the heat exchanger can be in the form of a capillary tube. The capillary tube has an inside diameter which is small enough to produce appropriate desired capillary effects when the heat exchanger is in operation. The capillary tube can be dimensioned here in dependence on the heat transfer fluid flowing through the heat exchanger.

The conduit of the heat exchanger can be integrated in a mat, the contour of which is adapted to a contour of a section of the vehicle outer skin via which the heat exchanger section is thermally coupled to the outside environment. The mat can be made, for example, of a plastic material, a plastic foam or a fibrous material and be provided for fastening to an inner surface of the vehicle outer skin. Particularly simple mounting of the mat on the inner surface of the vehicle outer skin is possible when the mat has a certain flexibility. Alternatively to this, however, it is also conceivable to fasten the conduit of the heat exchanger directly to the vehicle outer skin.

The material of the mat can be chosen, depending on the particular application, such that the mat has desired thermal conductivity properties. For example, it is conceivable to lay the conduit, which is integrated in the mat, in the region of a surface of the mat which faces the vehicle outer skin, and to produce the mat from a material with a low thermal conductivity. The mat then has a certain insulating effect. Alternatively to this, the mat can be made of two different materials with different thermal conductivities. A layer having a high thermal conductivity can then produce the thermal coupling to the vehicle outer skin and ensure a good heat transfer to the outside environment. A layer having a low thermal conductivity can, in contrast, form a surface of the heat exchanger facing away from the vehicle outer skin and ensure a certain insulating effect.

Preferably, the mat with the integrated conduit is detachably fastened to the section of the vehicle outer skin via which the heat exchanger section is thermally coupled to the outside environment. The mat with the integrated conduit can then be simply mounted on the vehicle outer skin and also simply detached from the vehicle outer skin again, for example for inspection purposes. Suitable fastening means for the detachable fastening of the mat with the integrated conduit to the section of the vehicle outer skin forming the section of the heat exchanger which is thermally coupled to the outside environment comprise, for example, screws, touch-and-close connections, adhesive-bonded connections, etc.

A liquid heat transfer fluid can flow through the cooling circuit of the cooling system according to the invention. A liquid heat transfer fluid is advantageous particularly when large quantities of heat have to be removed from the heat-loaded device. Furthermore, a cooling circuit through which flows a liquid heat transfer fluid can be used particularly advantageously when it serves to remove heat from a plurality of heat-loaded devices arranged in a manner distributed in the vehicle. Alternatively to this, a two-phase heat transfer fluid can also be employed in the cooling circuit of the cooling system according to the invention, which fluid evaporates owing to the heat absorption from the heat-loaded device and is transformed back into the liquid state again on cooling.

Furthermore, air can also flow through the cooling circuit. This is particularly expedient when the heat-loaded device to be cooled is arranged in the vicinity of the vehicle outer skin. For example, air can be sucked out of a hold or another region of an aircraft and supplied to the heat exchanger of the cooling system according to the invention via the cooling circuit. In the heat exchanger, the air sucked out of the hold or the other region of the aircraft can be cooled by heat exchange with the ambient or outside air to a desired low temperature, before being led back to the hold or the other region of the aircraft again.

A method according to the invention for cooling a heat-loaded device in a vehicle, particularly an aircraft, comprises the steps of conveying a heat transfer fluid through a cooling circuit which is thermally coupled to the heat-loaded device in order to remove heat from the heat-loaded device, and thermally coupling the heat transfer fluid, flowing through the cooling circuit, to a heat exchanger. The heat exchanger releases the heat supplied to it by the heat transfer fluid to the outside environment via a section thermally coupled to an outer skin of the vehicle.

The present invention can be advantageously used in vehicles, such as, for example, motor vehicles but also trains, particularly however in aircraft. The present invention can be used particularly advantageously in an aircraft which comprises an air conditioning system described in the German patent application 10 2007 049 926, since in this aircraft at least parts of the aircraft outer skin in the region of the aircraft fuselage lower shell do not have to be provided with an inner insulation. The content of the German patent application 10 2007 049 926 is incorporated herein by reference.

A preferred embodiment of a cooling system according to the invention is now explained in more detail with reference to the attached schematic drawings, of which

FIG. 1 shows a cooling system for cooling a heat-loaded device on board an aircraft, and

FIG. 2 shows a cross-sectional illustration of a heat exchanger used in the cooling system according to FIG. 1.

An aircraft cooling system 10 shown in FIG. 1 comprises a cooling circuit 12, through which flows a heat transfer fluid and which is thermally coupled to a heat-loaded device 14 in order to remove heat from the heat-loaded device 14. A conveying device 16 in the form of a pump conveys the heat transfer fluid through the cooling circuit 12. A heat exchanger 18 is integrated in the cooling circuit 12 and the heat transfer fluid circulating in the cooling circuit 12 flows through the heat exchanger 18.

The heat transfer fluid circulating in the cooling circuit 12 and heated by the thermal contact with the heat-loaded device 14 is cooled in the heat exchanger 18 by heat removal to the ambient or outside air. In other words, the heat exchanger 18 uses the ambient or outside air as a heat sink for the heat to be removed from the heat-loaded device 14. For this purpose, the heat exchanger 18 has a section 20 which faces the outside environment and is thus thermally coupled to the outside environment, and which is connected to an aircraft outer skin 22 and is thereby thermally coupled to the aircraft outer skin 22. The section of the aircraft outer skin 22 via which the heat exchanger section 20 is thermally coupled to the outside environment is arranged in the region of an aircraft fuselage lower shell 24, where the aircraft outer skin 22 is not provided with an inner insulation (not shown in FIG. 1), unlike in the region of an aircraft fuselage upper shell 26.

As can be seen particularly in FIG. 2, the heat exchanger 18 extends sheet-like between stringers 28, which stiffen the aircraft fuselage lower shell 24, and frames, not shown in FIG. 2. The heat exchanger 18 comprises a conduit 30 in the form of a capillary tube, which is integrated in the cooling circuit 12 of the cooling system 10 and through which flows the heat transfer fluid circulating in the cooling circuit 12. The conduit 30 is integrated in a mat 32 made of a fibrous material and extends with a multiplicity of turns through the mat 32. A shape and contour of the mat 32 is adapted to a shape and contour of the section of the aircraft outer skin 22 via which the heat exchanger section 20 is thermally coupled to the outside environment. In other words, the contour of the mat 32 has a curvature adapted to a curvature of the aircraft outer skin 22. The mat 32 with the integrated conduit 30 is detachably fastened to the aircraft outer skin 22. 

1-10. (canceled)
 11. Cooling system for cooling a heat-loaded device in a vehicle, particularly an aircraft, having: a cooling circuit, through which flows a heat transfer fluid and which is thermally coupled to the heat-loaded device in order to remove heat from the heat-loaded device, and a heat exchanger comprising a section which is thermally coupled to the outside environment via an outer skin of the vehicle, the heat exchanger comprising a conduit which is thermally coupled to the cooling circuit, characterised in that the conduit of the heat exchanger is in the form of a capillary tube and is integrated in a mat, the contour of which is adapted to a contour of a section of the vehicle outer skin via which the heat exchanger section is thermally coupled to the outside environment.
 12. Cooling system according to claim 11, characterised in that the section of the heat exchanger is thermally coupled to the outside environment via an aircraft outer skin.
 13. Cooling system according to claim 12, characterised in that the section of the heat exchanger is thermally coupled to the outside environment via a section of the aircraft outer skin arranged in the region of an aircraft fuselage lower shell.
 14. Cooling system according to claim 11, characterised in that the heat exchanger is integrated in the outer skin of the vehicle in such a way that the section of the heat exchanger thermally coupled to the out-side environment is formed by a section of the vehicle outer skin.
 15. Cooling system according to claim 11, characterised in that the mat with the integrated conduit is detachably fastened to the section of the vehicle outer skin via which the heat exchanger section is thermally coupled to the outside environment.
 16. Cooling system according to claim 11, characterised in that a liquid heat transfer fluid or air flows through the cooling circuit.
 17. Method for cooling a heat-loaded device in a vehicle, particularly an aircraft, having the steps of: conveying a heat transfer fluid through a cooling circuit which is thermally coupled to the heat-loaded device in order to remove heat from the heat-loaded device, and thermally coupling the heat transfer fluid, flowing through the cooling circuit, to a heat exchanger, the heat exchanger releasing the heat supplied to it by the heat transfer fluid to the outside environment via a section thermally coupled to an outer skin of the vehicle and the heat exchanger being thermally coupled to the cooling circuit by means of a conduit, characterised in that the conduit of the heat exchanger is in the form of a capillary tube and is integrated in a mat, the contour of which is adapted to a contour of a section of the vehicle outer skin via which the heat exchanger section is thermally coupled to the outside environment. 